DNA vaccines represent an emerging field which provides the means to prevent and treat disorders, diseases, conditions and infections by inducing immune responses in individuals which are directed at antigens associated with such disorders, diseases, conditions and infections. Essentially, plasmid DNA that includes coding sequences for antigens operably linked to regulatory elements required for gene expression is administered to individuals. The cells of the individual take up the plasmid DNA and the coding sequence is expressed. The antigen so produced becomes a target against which an immune response is directed. The immune response directed against the antigen provided the prophylactic or therapeutic benefit to the individual against any allergen, pathogen, cancer cell or autoimmune cell that includes an epitope that is recognized by the immune response against the antigen.
DNA vaccines include naked and facilitated vaccines. Further, they may be administered by a variety of techniques including several different devices for administering substances to tissue. The published literature includes several review articles that describe aspects of DNA vaccine technology and cite some of the many reports of results obtained using the technology. The following review articles which are each incorporated herein by reference as are each of the references cited in each review article discuss DNA vaccine technology: McDonnel W. M and F. K. Askari 1996 New Engl. J. Med. 334(1)42-45; Robinson, A. 1995 Can. Med. Assoc. J. 152(10):1629-1632; Fynan, E. F. et al. 1995 Int. J. Immunopharmac. 17(2)79-83; Pardoll, D. M. and A. M. Beckerleg 1995 Immunity 3:165-169; and Spooner et al. 1995 Gene Therapy 2:173-180.
While such vaccines are often effective to immunize individuals prophylactically or therapeutically against pathogen infection or human diseases, there is a need for improved vaccines. There is a need for compositions and methods which produce an enhanced immune response.